1. Field of the Invention
The present invention relates to the field of cancer diagnosis and diagnostic means therefor.
2. Description of Related Art
Thyroid nodules are endemic in iodine deficient areas, like Europe's alpine regions, where they have a prevalence of 10-20%. They are classified by their histology into the 2 benign types Struma nodosa (SN) and Follicular Thyroid Adenoma (FTA) and the malignant entities Follicular Thyroid Carcinoma (FTC), Papillary Thyroid Carcinoma (PTC), Medullary Thyroid Carcinoma (MTC) and Anaplastic Thyroid Carcinoma (ATC). Conventionally, discrimination between benign and malignant thyroid nodules is done by scintigraphy and fine needle aspiration followed by histology. Despite many advances in the diagnosis and therapy of thyroid nodules and thyroid cancer, these methods have a well-known lack of specificity, particularly for the discrimination between FTA and FTC, which leads to a number of patients unnecessarily treated for malignant disease.
Given the diagnostic limitations of previous methods, in particular fine needle aspiration followed by cytology, multiple investigators have carried out expression profiling studies with hopes of identifying new diagnostic tools. Such analyses attempt to identify differentially expressed genes with an important role in disease development or progression using large-scale transcript-level expression profiling technologies such as cDNA microarrays, oligonucleotide arrays and Serial Analysis of Gene Expression (SAGE). Typically, dozens or hundreds of genes are identified, many of which are expected to be false positives, and only a small fraction useful as diagnostic/prognostic markers or therapeutic targets (Griffith et al., J Clin Oncol 24(31):5043-5051 (2006)).
In other types of cancer it has been shown that gene expression profiling can add substantial value to the discrimination of the different clinically relevant tumour-entities. The US 2006/183141 A e.g. describes classification of tumor markers from a core serum response signature. Different studies have tried to classify the different entities of thyroid carcinoma on the basis of their gene expression profiles each of them discriminates between 2 of the 5 entities. However, the studies have no or very few genes in common and applying a classier from one study to the data from another study generally yields poor classification results.